Generally, in the conventional optical pulse signal receiving circuit, the output voltage has been amplified by an operational amplifier and the like with the help of light receiving elements such as a phototransistor.
However, in the conventional receiving circuit, the optical pulse signal received was distorted, e.g., during rise of the output amplitude or when the pulse voltage is reduced, due to response characteristics of the phototransistor, operational amplifier, and the like. In particular, where multistep transmission of data is to be made by reproducing an optical signal on the basis of the received signal, cases have occurred in which distortions of the signals are combined to become a serious defect for practical use. Also, optical pulse signals are not necessarily received in the same strengths because of attenuation thereof during transmission. Therefore, it has been necessary to provide a signal strength correction circuit, especially where multistep transmission of data is to be made.